Changes

* Reviews and Driving

* Fix hang on shutdown if you shutdown immediately after closing a compose window where you've done autocomplete against ssl ldap, r=standard8, {{bug|420744}}

* Only display start page once per life of thread pane/tab, part of {{bug|520272}}, speed up opening folders

* Make sure streaming imap messages with aLocalOnly set doesn't sometimes fetch message from server, especially for compact offline store case, {{bug|519801}}